Contents

? 1. Summary

? 2. Technology Description

? 3. Performance

? 4. Technology Applicability & Alternatives

? 5. Cost

? 6. Regulatory/Policy Issues

? 7. Lessons Learned

? Appendices

Summary

Technology DescriptionIn Situ Bioremediation (ISB), which is the term used in this report for Gaseous NutrientInjection for In Situ Bioremediation, remediates soils and ground water contaminatedwith volatile organic compounds (VOCS) both above and below the water table. ISBinvolves injection of air and nutrients (sparging and biostimulation) into the ground waterand vacuum extraction to remove VOCs from the vadose zone concomitant withbiodegradation of VOCS.

The innovation is in the combination of 3 emerging technologies: air stripping, horizontalwells, and bioremediation via gaseous nutrient injection with a baseline technology, soilvapor extraction, to produce a more efficient in situ remediation system.

? Horizontal wells provide a more effective access to subsurface contamination.

? The air sparging/gaseous nutrient injection process eliminates the need for surface ground watertreatment systems and treats the subsurface, both unsaturated and saturated zones, in situ.

? The air sparging/gaseous nutrient injection process stimulates the growth of indigenousmicroorganisms in the contaminated zone to degrade and mineralize VOCS. Soil vapor extractioncan be combined with the injection process to strip the higher concentration, more easily removedcontaminants from the subsurface. The injection/extraction system can be designed to meet sitespecific needs.

? The types of sites most likely to apply ISB will contain moderately permeable, relativelyhomogenous sediments contaminated with VOCs, especially if both an extraction and injectioncomponent is utilized. However, the presence of clay strata does not preclude its use. In fact, the

bioremediation component may be well applied to enhance degradation and/or removal of VOCsfrom lower permeability zones.

Technology StatusA full-scale demonstration was conducted as part of the Savannah River IntegratedDemonstration: VOCs in Soils and Ground Water at Nonarid Sites.

U.S. Department of EnergySavannah River SiteM Area Process Sewer/Integrated Demonstration SiteAiken, South CarolinaFebruary 1992 to April 1993

? A group of nationally recognized experts from the U.S. Department of Energy (DOE), theU.S. Air Force, the U.S. Geological Survey, the U.S. Environmental Protection Agency,industry, and academia met regularly for 3 years to provide unique insights for planning,execution, and evaluation of this technology demonstration.

? The demonstration site was located at one of the source areas within the one-square mile VOCground water plume. Prior to application of ISB, trichloroethylene (TCE) andtetrachloroethylene (PCE) concentrations in ground water ranged from 10 to 1031 ug/L and 3to 124 ug/L, respectively. TCE and PCE concentrations in sediments ranged from 0.67 to 6.29mg/kg and 0.44 to 1.05 mg/kg. The site is underlain by a thick section of relatively permeablesands with thin lenses of clayey sediments. Appendix A describes the site in detail.

Key Results

? Almost 17,000 lbs. of VOCs were removed or degraded over 384 days of operation. Thevacuum component of ISB removed 12,096 lbs. VOCs and the biological componentdegraded and mineralized an additional 4,838 lbs. VOCS.

? Mass balance calculations indicate that bioremediation destroyed 40% more VOCs thansimple air sparging (i.e., in situ air stripping).

? Gaseous nutrient injection of carbon, nitrogen, and phosphorus was achieved simultaneouslyfor the first time and demonstrated better mass transfer than previous methods of liquidnutrient injection.

? This nutrient injection strategy stimulated a specific functional group of bacteria that is knownto degrade specific contaminants.

? No toxic intermediates were produced by the bioremediation strategy. Contaminants werecompletely mineralized.

? The best operating campaign used continuous air and nutrient injection (N & P) plus thepulsed addition of 4% methane.

? Los Alamos National Laboratory (LANL) completed a cost-benefit analysis showing that ISBcould reduce costs by over 30% compared to the baseline technology of an integrated SoilVapor Extraction/Pump- and-Treat System (SVE/PT).

? ISB could reduce the time required to remediate a site by 5-7 years compared to the baselinetechnology of SVE/PT.

The ISB process is patented by the Department of Energy and has been licensed to six commercial vendorswith 13 new applications pending. Two companies are using the technology in the field. Licenses areavailable through the Westinghouse Savannah River Company (WSRC).

ContactsTechnical

Terry Hazen and Brian Looney, Principal Investigators, WSRC, (803) 725-6413 and (803) 725-3692.

ManagementKurt Gerdes, DOE EM-50, DOE Integrated Demonstration Program Manager, (301) 903-7289.Jim Wright, DOE Plumes Focus Area Implementation Team Manager, (803) 725-5608.

Licensing InformationCaroline Teelon, Technology Transfer Office, WSRC, (803) 725-5540.

Technology Description

Overall Process Schematic

? Air, methane, nitrous oxide, and triethyl phosphate were injected through the lower horizontalwell, below the water table.

? An air/contaminant mixture was extracted from the upper horizontal well, above the watertable.

? Offgas treatment used catalytic oxidation for the demonstration, but other technologies areavailable for the treatment of offgases.

? Indigenous methanotrophic bacteria can oxidize methane via a series of enzymes (e.g.,methane monooxygenase). Methane monooxygenase, an extremely powerful oxidizer,induces the formation of TCE-epoxide from TCE. TCE epoxide is extremely unstable andspontaneously breaks down. The final and almost immediate end product is carbon dioxideand chloride salts.

Appendix B provides detailed information about the horizontal well installations and themonitoring wells installed.

Aboveground SystemNotes:

? Air-water separator removes debris and moisture from the air stream. System includes a daytank to drain water from separator for treatment at M-Area air stripper.

? Demonstration generated VOCs that were treated by electrically heated catalytic oxidation ofthe offgas.

Performance

Demonstration Plan? Performance of the technology has been assessed using information from the full-scale

demonstration at SRS. Six different operational modes were tested during the demonstration.

? Major elements of the demonstration included:

o initial vapor extraction of vadose zone gases (20 days),

o addition of air sparging by simultaneous air injection into the saturated zone and vaporextraction from the vadose zone (33 days),

o a planned series of nutrient additions:

? 1% methane addition (107 days),

? 4% methane addition (79 days),

? pulsed 4% methane addition operated at long and short intervals (94 days),

? continuous addition of gaseous nutrients in the form of 0.07% nitrous oxide and0.007% triethyl phosphate in air in combination with pulses of 4% methane (94days),

? assessment of the behavior of injected methane in air through an inert gas (helium) tracer test, and

? comparison of microbiological assays for monitoring and control of in situ bioremediation.

Treatment PerformanceSummary? Air-nutrient injection/extraction removed VOCs from the subsurface and degraded VOCs in place.

? Biostimulation and biodegradation occurred in situ without producing toxic daughter products.

o Increases in indigenous methanotrophs and in C02 concentrations in soil gas andextraction well gas imply significant microbial community degradation of methane andTCE.

o Decreases in methane and TCE in the subsurface coincided with increases in densities ofmethanotrophs (up to 7 orders of magnitude) and free chloride ion as a result ofbiodegradation.

o Addition of continuous 4% methane initially stimulated microbial populations but led tonutrient depletion, which then decreased the microbial population.

o Addition of nitrogen and phosphorus nutrients with pulsed methane resulted in enhancedand sustained microbial growth that optimized bioremediation and mineralization of TCEand PCE in ground water and sediments.

? ISB has demonstrated reduction of VOC concentrations in ground water below the Safe DrinkingWater Act maximum of 5 ppb for TCE/PCE. Overall ground water concentrations decreased by asmuch as 95%.

? Cleanup of VOCs in the vadose zone was very effective. Most sediments contained nondetectableconcentrations of VOCs after the demonstration was completed. Soil gas concentrations decreasedby more than 99%.

? Average daily emissions from the offgas stream were less than the minimum detection of 1.9lb./day. Greater than 94% of VOCs were treated by the catalytic oxidation unit.

Key System Parameters? Horizontal Well Placement

o The lower injection horizontal well was placed below the water table (120 feet) at a depthof 175 feet with a screened length of 310 feet.

o The upper extraction horizontal well was placed in the vadose zone above the water tableat a depth of 80 feet with a screened length of 205 feet.

? Vacuum Applied

o Air was extracted continuously from the upper vadose zone horizontal well (AMH-2) at240 scan.

? Air Injection

o Air plus nutrients were injected into the lower aquifer horizontal well (AMH-1) at 200scfm.

? Nutrient Injection Campaigns

o 1% methane was initially injected continuously.

o Methane concentration was increased to 4%.

o Methane injection was maintained at 4% but it was applied in pulses.

o Pulsed 4% methane injection was supplemented with continuous injection of 0.07%nitrous oxide and 0.007% triethyl phosphate in air to supply nitrogen and phosphaterequired for sustained microbial growth and metabolism.

? Microbial Activity

o Prior to ISB, subsurface ground water and vadose zone bacterial populations were low,and the microbial population was under nutrient stress.

o The addition of methane specifically stimulated the growth of methanotrophs, thebacteria primarily responsible for degradation of TCE.

Biostimulation? Evidence of biostimulation: densities of methanotrophs and methylotrophs in the ground water

increased as TCE decreased.

Amount of VOCs Removed or Degraded in Place

? Almost 17,000 lbs. of VOCs were removed over 384 days of operation.

o The vacuum component of ISB removed 12,096 lbs. VOCs and the biological componentdegraded and mineralized an additional 4,838 lbs. VOCS. Figures showing theconcentrations of TCE and PCE in the sediments before and after the demonstration(following) were used to calculate the mass degraded in place.

Concentration of TCE in Sediments Before and After ISB

? Sediment data are known to underestimate the amount of VOCs at the demonstration site, but canbe used to develop a sense of relative amounts of contamination removed or degraded in placeduring the demonstration.

? The total sediment inventory for both TCE and PCE decreased by 24%.

Concentration of PCE in Sediments Before and After ISB

? Sediment data are known to underestimate the VOCs at the demonstration site, but can beused to develop a sense of relative amounts of contamination removed or degraded in placeduring the demonstration.

? The total sediment inventory for both TCE and PCE decreased by 24%.

Results of Helium Tracer Test

? A helium tracer test was used to predict the fate of the injected methane.

o Based on helium breakthrough curves, the amount of methane that should have beenobserved in the extraction well was calculated.

o More than 50% of the injected methane was removed before it reached the extractionwell.

? Microbial metabolism consumed the methane that did not reach the extraction well.

Zones of Influence

? The extraction well in the vadose zone created a zone of influence estimated to be greater than 200ft based on pressure measurements.

? Electrical resistance tomography was used to map a sparge zone of influence in the saturated zone.These data showed that flow paths were confined to a complex three-dimensional network ofchannels, some of which extended as far as 100 feet from the injection well.

? Methane was detected at distances over 500 feet from the injection well.

Technology Applicability and Alternative Technologies

Technology Applicability? ISB via Gaseous Nutrient Injection has been demonstrated to remediate soils, sediments, and

ground water contaminated with VOCs both above and below the water table. The gaseousnutrient injection system can be designed for application only in the unsaturated zone as an add-onto the bioventing process.

? The geometry of horizontal well treatment conforms to typical subsurface contaminated zones,which are often relatively thin but laterally extensive areas.

? ISB is not well suited for extremely low permeability sites if injection and extraction is utilized.Some permeability is required to deliver the nutrients to the indigenous microorganisms.

? At some sites ISB could be most effective when used in conjunction with in situ air stripping, thatis if situ air stripping is applied first at a site to quickly remove high concentrations ofcontaminants from source areas and then ISB is applied as a polishing step to removecontaminants present at lower concentrations. At other sites ISB only would be utilized, thusminimizing the amount of contaminants removed from the subsurface needing treatment as offgasat the surface.

? ISB has demonstrated that it can clean up ground water to drinking water standard concentrations.Sufficient information on cleaning up an entire site to these standards is not available.

? Commercialization and intellectual property information is included in Appendix D.

Competing Technologies? ISB with Gaseous Nutrient Injection is competitive with conventional baseline technologies of

pump-and-treat and pump-and-treat combined with soil vapor extraction. Numerous otherphysical/chemical, thermal, and biological technologies are also either available or underdevelopment to treat VOC-contaminated soils and ground water either in situ or above ground.

? The effectiveness of ISB was compared with performance data from air sparging and soil vaporextraction alone (VOCs removed through the offgas treatment system). This comparison was usedas the basis of the cost analysis discussed in the Cost section.

? Air sparging in vertical wells and in well recirculation technologies have been implemented atsimilar sites across the U.S. and in Europe. Thermal technologies have more often been applied atsites with less permeable sediments. Deep soil mixing has been applied at sites with shallowercontamination.

Technology Maturity? Stimulation of indigenous methanotrophic bacteria by injection of methane in water was

demonstrated at a small sandy field site at Moffett Field in California, forming the technical basisfor the design of this demonstration. However, the Moffett Field demonstration involved additionof nutrients as liquids rather than gases. The SRS demonstration was the first gaseous nutrientinjection demonstration designed for stimulation of methanotrophs.

? Much laboratory and bench-scale work has been completed to verify the technical basis for thedemonstration.

? ISB via Gaseous Nutrient Injection is currently being applied at two industrial sites and is plannedfor implementation at the Savannah River Site Sanitary Landfill and the M-Area IntegratedDemonstration Site. It has also been proposed at a number of other industrial sites.

? A market survey on horizontal environmental wells was completed in 1993. Key results of thatstudy included:

o Since 1987, over 100 horizontal environmental wells have been installed in the U.S.

o 25% of the wells have been used for ground water extraction, 25% for soil vaporextraction, and 50% for other purposes, such as air injection, bioventing, and petroleumrecovery.

o 80% of the horizontal wells have been installed at vertical depths of 25 feet or less.

o The rate of horizontal well installations has increased significantly in the last two yearspossibly because of more widespread recognition of advantages and improvements indrilling techniques, which have made installation more cost effective. A cursory updateof the 1993 survey has shown that between July 1993 and December 1994 more than 50horizontal environmental wells were installed.

Cost

Introduction? Information in this section was prepared from data provided by the SRS VOCs in Soils and

Ground Water at Non-arid Sites Integrated Demonstration to the Los Alamos National Laboratory,tasked by the DOE Office of Technology Development to perform an independent cost analysis ofthe technology being demonstrated.

? The mass of contaminant removed or degraded by in situ biological processes is difficult toquantify.

o Mass balance determinations relied upon data collected by sampling and analyzingsediment, air, and ground water samples, and by contaminant plume modeling.

? The conventional technology of integrated pump and treat combined with soil vapor extraction(PT/SVE) was used as the baseline technology, against which ISB was compared. To compare the tworemediation systems, a number of assumptions were made:

o PT/SVE would remove the same amount of VOCs as the vacuum component of ISBwhen operated for the same time period.

o 4 vertical SVE and 1 PT wells would have the same zone of influence as 2 horizontalwells used for ISB.

o Volatilized contaminants from both technologies are sent to a catalytic oxidation systemfor destruction.

o Capital equipment costs are amortized over the useful life of the equipment, which isassumed to be 10 years, not over the length of time required to remediate a site.

Capital Costs

? Capital costs for the baseline technology are comparable with the innovative technology of ISB.

o The cost to install horizontal wells for ISB exceeds installation costs of vertical wells.However, horizontal drilling costs are decreasing as the technology becomes more widelyused and accepted. If horizontal wells can clean a site faster, significant dollars will besaved on operating costs.

o Fixed equipment costs for ISB include gas mixing and injection equipment for providingthe nutrients required for stimulation of the bioremediation portion of the innovativetechnology.

Capital Costs ISB PT/SVE______________________________________________________________________________Site Cost $5,400 $7,500Equipment Cost $9,200 $32,000Design and EngineeringMobile Equipment $18,000 $18,000Well Installation $183,000 $50,690Other Fixed Equipment $183,732 $168,665Mobilization Cost $43,075 $64,613 _________ _________Total Capital Equipment and $452,407 $341,468Mobilization Costs

Operating Costs? The annual operating costs are comparable between the baseline and the innovative remediation

technology.

? However, the treatment time is estimated to be 10 years to remediate the demonstration site usingthe baseline PT/SVE and only 3 years using ISB. Actual treatment times are estimates and fieldexperience indicates that the PT/SVE estimate is on the optimistic side, when the objective is theSafe Drinking Water Act (SDWA) maximum of 5 ppb for TCE/PCE.

Operation and Maintenance Costs ISB PT/SVE__________________________________________________________________________________Monitoring/Maintenance $71,175 $71,175Consumable Cost $122,215 $123,595Demobilization Costs $43,075 $64,613 __________ __________Total Operational and Maintenance $236,465 $259,383 Costs

? Consumable and labor costs are approximately 85% of the total cost per pound of the VOCsremediated for both technologies.

? The length of time that the ISB system operated determines the quantity of VOCs remediated. Thedemonstration was operated for 384 days.

? Mass balances calculated that 41% more VOC destruction occurred with ISB than with airsparging (using the same operating parameters) because of biological remediation.

? A model developed by LANL during the demonstration predicts that after 3 years the quantityremediated would have been 90%.

? The worst case scenario would be no additional destruction because of biological stimulation, butthis would still produce a reduction in remediation cost over the baseline technology.

Regulatory/Policy Issues

Regulatory Considerations? Permit requirements for the demonstration were controlled by the South Carolina Department of

Health and Environmental Control (SCDHEC) and included 1) an Air Quality Permit and 2) anUnderground Injection Control (UIC) Permit issued by the South Carolina Board of DrinkingWater Protection. A NEPA checklist was also prepared; a categorical exclusion was granted. U.S.Department of Transportation (DOT) certification was required to transport methane to theremediation site.

? Permit requirements for future applications of ISB are expected to include:

o An air permit for discharge of treated vapor extracted from the subsurface,

o CERCLA and/or RCRA permitting depending on site specific requirements,

o Underground injection permits for the injection of methane and nutrients into thesubsurface,

o NEPA review for federal projects, and

o U.S. DOT certification for transportation of methane to the remediation site.

? Permit requirements will differ from state to state.

? Groundwater protection standards (GWPS) have been established as part of a RCRA permit forthe M-Area. The GWPS'are based upon EPA Maximum Contaminant Levels (MCLs). Specificgoals for contaminants of greater concern are:

Compound Concentration (ppb) __________________________________________________ TCE 5 PCE 5 TCA 200

Safety, Risks, Benefits, and Community ReactionWorker Safety? Health and safety issues for the installation and operation of ISB are essentially equivalent to those

for conventional technologies of pump-and-treat or soil vapor extraction.

? Additional permitting and training were required for transportation and delivery of methane andfor the operation of the methane injection system.

? Methane concentrations were always far below the explosive limit to minimize any danger toonsite workers. A process hazards review was completed to ensure safe operations.

? Level D personnel protection was used during installation and operation of the system.

Community Safety? ISB with an operational offgas treatment system does not produce any significant routine release

of contaminants.

? No unusual or significant safety concerns are associated with the transport of equipment, samples,waste, or other materials associated with ISB.

? Careful and thorough monitoring of the subsurface sediments and ground water shows thatpotential harmful or disease-causing microorganisms are not present or stimulated by ISB at thedemonstration site.

Environmental Impacts? ISB systems require relatively little space, and use of horizontal wells minimizes clearing and

other activities that would be required to install a comparable vertical well network.

? Visual impacts are minor, but operation of the vacuum blower and compressor create moderatenoise in the immediate vicinity.

? Nutritional enrichment does not promote the growth of harmful microbes at the demonstrationsite.

Socioeconomic Impacts and Community Perception? ISB has a minimal economic or labor force impact.

? The general public has limited familiarity with ISB; however, the technology received positivesupport on public visitation days at SRS.

? Bioremediation in general is viewed by the public as a "green" technology, which enhancesnaturally occurring processes to destroy contaminants.

Lessons Learned

Design Issues? Gaseous nutrient injection represents a significant new delivery technique for in situ

bioremediation.

? Rates of air extraction (or whether to extract at all) and rates of air/nutrient injection must betailored to site specific needs.

? The bundle-tube pressure sensors installed along Horizontal Wells 1 and 2 to measureinjection/extraction efficiency are inexpensive and recommended for future applications.

? Factors that will control injection protocols, remediation system siting, and monitoring include sitegeology (especially permeability and heterogeneity), concentrations of native nutrients (such astotal organic carbon), natural oxidation potential of the subsurface (i.e. aerobic or anaerobicconditions).

? The filter pack on all the horizontal wells is made up of natural formation solids, principallybecause of collapse around the borehole. This may diminish well efficiencies. Well design must betailored to the ultimate use of the well. Prepacked screen should only be used if necessary becauseit adds significantly to the cost.

? A horizontal well in the unsaturated zone removes water from the formation; the water can collectin the well, reducing its effective length. Wells must be designed to channel water away from lowareas.

? Careful alignment of the injection and extraction wells is probably not necessary because the zoneof influence of the extraction well is far greater than that of the injection well and becausesubsurface heterogeneities strongly influence air flow.

Implementation Considerations? Separate components of the system may be utilized for a particular application or the system may

be used in total as demonstrated at the Savannah River Site.

o For example, the system can be used with or without horizontal wells.

o Another option involves design of a system that does not have the vapor extractioncomponent. In this case, biodegradation of contaminants is optimized but nocontaminants are removed via a physical process.

o At some sites the addition of methane may not be required at all or at least initially,because there is naturally a sufficient carbon source for the indigenous methanotrophs.

? The optimum operating campaign involved pulsed injection of methane (4%) combined withcontinuous injection of air with nutrients (nitrogen and phosphorus).

? Automated control and monitoring functions added significantly to the ease and cost of operationof the system.

? A pulsing regime for the gaseous nutrients can be designed to accomplish both aerobic andanaerobic degradation simultaneously. For example, at SRS both TCE and PCE were biodegraded.

This required both aerobic and anaerobic degradation. It is believed that anaerobic pockets werecreated in the subsurface, which led to degradation of PCE within an overall aerobic system.

? Horizontal drilling methods must be tailored to specific site conditions with special considerationsfor the type of drilling fluid, drilling bit, drilling methodology, casing installation, etc.

Technology Limitations/Needs for Future Development? Long-term performance data from several years of operation varying operating parameters are

required to assess the need for design improvements and to better quantify life-cycle costs.

? Better monitoring methods for determining mass balance and microbiological health of thesubsurface population are required to facilitate implementation of ISB.

? It is possible that subsurface injection of gases below the water table can induce ground waterflow. In such a case, ISB could accelerate lateral migration of contaminants in certain geologicsettings. If clay layers or other geologic features constrict vertical flow, it may be necessary to useISB in conjunction with a pump-and-treat system for hydraulic control.

? There was no evidence of plugging of the wells as a result of the increased subsurface biomassthat resulted from the subsurface injection of nutrient gases.

? More experience with environmental horizontal drilling under a variety of subsurface conditionswill ensure better well installations at reduced costs.

Technology Selection Considerations? The cost of adding methane injection to an air sparging system is relatively low and easily

recovered (nearly all water samples showed greater than 90% mineralization of TCE and PCE bymethanotrophs after nutrients were added to the system).

? This technology yields significant economic and efficiency gains over conventional baselinetechnologies for remediation of ground water and sediment contaminated with chlorinatedsolvents.

? One application of the ISB system can be as a polishing technique after high concentrations areremoved by In Situ Air Stripping using horizontal wells. This approach would likely be used atsites where initial contaminant concentrations are high. On the other hand, the biologicalcomponent may be most effective at sites with lower contaminant concentrations, ultimatelytargeting attainment of drinking water thresholds.

? The role of horizontal wells in improving the efficiency of remediation was assessed. Remediationefficiency may be enhanced by increased surface area for reaction, similarity of well profile andcontaminant plume geometry, borehole access to areas beneath existing facilities, and drillingalong facility boundaries to control plume migration. However, each site must be assessed for theutility of horizontal wells.

? Successful ISB requires good contact between injected air and contaminated soils and groundwater. An optimal geologic setting would have moderate to high saturated soil permeability, afairly homogeneous saturated zone to allow for effective injection of gaseous nutrients, andsufficient saturated thickness. Vadose zone characteristics would be moderate to high permeabilityand homogeneity.

? ISB using horizontal wells may be most applicable in linearly shaped plumes that are relativelythin.

Appendices

? Appendix A: Demonstration Site Characteristics

? Appendix B: Technology Description Detail

? Appendix C: Performance Detail

? Appendix D: Commercialization/intellectual Property

? Appendix E: References

Appendix A: Demonstration Site Characteristics

Site History/Background

? The Savannah River Site's historical mission has been to support national defense efforts throughthe production of nuclear materials. Production and associated research activities have resulted inthe generation of hazardous waste by-products now managed as 266 waste management unitslocated throughout the 300 square mile facility.

? The A and M Areas at Savannah River have been the site of administrative buildings andmanufacturing operations, respectively. The A/M-Area is approximately one mile inward from thenortheast boundary of the 300 square mile Savannah River Site. Adjacent to the site boundary arerural and farming communities. Specific manufacturing operations within the M-Area includedaluminum forming and metal finishing.

? The M-Area operations resulted in the release of process wastewater containing an estimated 3.5million lbs. of solvents. From 1958 to 1985, 2.2 million lbs. were sent to an unlined settling basin,which is the main feature of the M-Area Hazardous Waste Management Facility (HWMF). Theremaining 1.3 million lbs. were discharged from Outfall A-014 to Tim's Branch, a nearby stream,primarily during the years 1954 to 1982.

? Discovery of contamination adjacent to the settling basin in 1981 initiated a site assessment efforteventually involving approximately 250 monitoring wells over a broad area. A pilot ground waterremediation system began operation in February l983. Full-scale ground water treatment began inSeptember l985.

? High levels of residual solvent are found in the soil and ground water near the original dischargelocations. Technologies to augment the pump-and-treat efforts, for example soil vapor extraction,ISAS, and bioremediation, have been tested and are being added to the permitted corrective action.

Contaminants of Concern

Contaminants of greatest concern are:

1,1,2-trichloroethylene (TCE)

tetrachloroethylene (PCE)

1,1,1 -trichloroethane (TCA)

Nature and Extent of Contamination? Approximately 71% of the total mass of VOCs released to both the settling basin and Tim's

Branch was PCE, 28% was TCE, and 1 % was TCA.

? The estimated amount of dissolved organic solvents in ground water in concentrations greater than10 ppb is between 260,000 and 450,000 lbs and is estimated to be 75% TCE. This estimate doesnot include contaminants sorbed to solids in the saturated zone or in the vadose zone. The area ofVOC-contaminated ground water has an approximate thickness of 150 feet, covers about 1200acres, and contains contaminant concentrations greater than 50,000 ug/L.

? DNAPLs found in 1991 present challenges for long-term remediation efforts.

? Vadose zone contamination is mainly limited to a linear zone associated with the leaking processsewer line, solvent storage tank area, settling basin, and the A-014 outfall at Tim's Branch.

Contaminant Locations and Hydrogeologic ProfilesSimplified schematic diagrams show general hydrologic features of the A/M Area atSRS.

Vadose Zone and Upper Aquifer Characteristics

Metal-degreasing solvent wastes were sent to the A-014 outfall and, via the process sewer, to the M-Areasettling basin. Data from hundreds of soil borings, ground water monitoring wells, and a variety of otherinvestigative techniques have established a well-documented VOC plume in both the vadose and saturatedzones.

TCE Concentrations in Soil (West-East Cross-Section)

Concentration and lithology data from 1991 along an approximately 200-ft cross-section across theintegrated demonstration site. Concentration contours of TCE in sediments are based on analysis of over1000 sediment samples. Highest concentrations of TCE occur in clay zones. These data were collectedbefore the in situ air stripping demonstration was conducted and do not represent pretest conditions for thein situ bioremediation demonstration.

Appendix B: Technology Description Detail

System Configuration

Horizontal Well Close-Ups

Horizontal Well Installation TechniquesThe techniques used to directionally drill and install a horizontal well depend on the location and purposeof the well. Petroleum industry technology was used to install Wells 1 and 2 at the Savannah River Site;however, this technology is no longer used. Current installation techniques include the following:

? Pipeline/Utility River Crossing System- Based on a mud rotary system used to drive a downholedrill assembly, including a drilling tool, a hydraulic spud jet with a 2-degree bend to providedirectional drilling or a downhole motor depending on the lithology to be drilled.

? Utility Industry Compaction System- Down hole drill assembly consists of a wedge-shapeddrilling tool and a flexible subassembly attached to the drill string. The borehole is advanced bycompaction, forcing cuttings into the borehole wall. Reduced volumes of water are introduced tocool the drill bit; no circulation of drilling fluid is accomplished.

? Hybrid Petroleum Industry/Utility Industry Technology- Modified mud rotary system withbottom hole assembly comprised of a survey tool, steerable downhole motor, and expandable-wing drill bit. Drilling fluids are used. Curve is drilled and pipe is installed in curve beforehorizontal is drilled. Only one company provides this type of drilling system.

Operational Requirements? Design and management of ISB systems require expertise in environmental, chemical, mechanical,

and civil engineering as well as hydrogeology and environmental regulations. Automation ofsystem operations with a real-time problem notification system reduced the manpowerrequirements significantly over that required for the earlier in situ air stripping demonstration.Operation of multiple systems of the scale implemented at the Savannah River Site can beperformed by a 1/6 full-time equivalent technician per system. Larger systems or extensivemonitoring activities would require additional staff.

Monitoring SystemsMonitoring wells and vadose zone piezometers had previously been installed at the site for the ISASdemonstration.

Ground Water Monitoring Well Clusters? Twelve borings were completed adjacent to 4-in. monitoring well clusters in the locations shown

in the following section.

? One well from each cluster was screened in the water table at elevations ranging from 216 to 244ft.

? The second well in the cluster was screened in the underlying semiconfined aquifer at elevationsranging from 204 to 214 ft.

? Four borings were completed at two times during the ISB demonstration: after the 1% methanecampaign and after the end of the pulsing campaign.

Vadose Zone Piezometer Clusters? Three borings were cored adjacent to piezometer clusters in the vadose zone.

? Three piezometer tubes having lengths of approximately 52 ft, 77 ft and 100 ft were installed intoeach borehole.

Geophysical Monitoring? ERT was performed in five borings. ERT maps the behavior of subsurface fluids as they change in

response to natural or remedial processes.

? Several single-point flow sensors were placed between the injection and extraction wells (justbelow the water table) to measure ground water flow in the area most affected by the ISB process.

Bundle Tubes

Appendix C: Performance Detail

Operational PerformanceMaintainability and Reliability? No functional problems encountered during demonstration; system was operational approximately

90% of all available time.

? Operational performance over long periods (years) not yet available.

Operational Simplicity? Monitoring performance of ISB is more difficult than monitoring performance of baseline pump-

and-treat technology; however, systems have been automated and can be operated and maintainedin the field typically by 1/6 full-time equivalent technician. Staffing requirements are detailed inAppendix B.

Demonstration ScheduleMajor Milestones of the Demonstration Program

Sampling, Monitoring, Analysis, and QA/QC IssuesObjectives? Gather baseline information and fully characterize site

? Evaluate removal efficiencies with time

? Evaluate subsurface microbial ecologies

? Identify and evaluate zones of influence

Baseline Characterization? Baseline characterization was performed before the demonstration to gather information on the

geology, geochemistry, hydrology, and microbiology of the site. The distribution of contaminantsin soils and sediments in the unsaturated zone and ground water was emphasized. These data werecompared with data on soil collected during and after the demonstration to evaluate theeffectiveness of ISB.

? Continuous cores were collected adjacent to monitoring well and vadose zone boreholes.Sediments for VOC analysis were collected at 5-ft intervals and at major lithology changes.Samples for microbiological characterization were collected every 10 ft.

? Water samples were collected and analyzed for VOC content and microbial characteristics frommonitoring well clusters and at discrete depths adjacent to monitoring well clusters.

? Geologic cross-sections were prepared using gamma ray, sp, resistivity, density, and neutrongeophysical logs and core logs.

Analytical Methods and Equipment? Vapor grab samples were analyzed in the field using both a Photo Vac field gas chromatograph

(GC) and a GC fitted with flame ionization and electron capture detectors. Analysis wasperformed immediately after collection.

? Bulk water parameters, including temperature, pH, dissolved oxygen, conductivity, and oxidationreduction potential, were measured using a Hydrolab.

? VOC analysis of water and sediment samples was performed on-site using an improvedquantitative headspace method developed by Westinghouse Savannah River Company. Analyseswere performed on an HP-5890 GC fitted with an electron capture detector and headspacesampler.

? Helium tracer samples were analyzed using a helium mass spectrometer modified to sample serumvials at a constant rate.

QA/QC Issues? Vapor samples were analyzed immediately after collection and GC analysis of soil and water

samples were completed less than 3 weeks after collection.

? Duplicate analysis was performed for nearly every water and sediment sample collected.

? Approximately 161 samples were analyzed off-site using standard EPA methods to corroborateonsite testing which used the improved quantitative headspace method described earlier. Cross-comparison showed that the quantitative headspace analysis generated equivalent to superior data.

? GC calibration checks were run daily using samples spiked with standard solutions.

Performance Validation? Samples analyzed onsite by nonstandard EPA methods were sent off site for confirmatory analysis

using EPA methods. Results from these analyses confirmed the findings of Savannah Riverefforts.

? The effectiveness of horizontal wells for environmental cleanup has been demonstrated by theiruse in vapor extraction and ground water/free product recovery systems which are also discussedin Appendix D.

Appendix D: Commercialization/Intellectual Property

Intellectual PropertyPrimary Sponsor

U.S. Department of Energy, Office of Environmental Management, Office of Technology Development

Existing/Pending Patents

Several parties, including national laboratories, industry, academia, EPA, USGS, USAF, participated in thedevelopment and implementation of the ISB system. These participants are listed in this document.

-- Patent 5,326,703, "Method and System for Enhancing Microbial Motility," T.C. Hazen and G. Lopez deVictoria, assignors to the U.S. as represented by the U.S. DOE.

-- Patent 5,324,661, "Chemotactic Selection of Pollutant Degrading Soil Bacteria," T.C. Hazen, assignors tothe U.S. as represented by the U.S. DOE.

-- Patent 5,384,048, "Bioremediation of Contaminated Groundwater," T.C. Hazen and C.B. Fliermans,assignors to the U.S. as represented by the U.S. DOE.

-- Patent Submitted 2/94, "Contactor System for Phosphorus Addition to Support Gas Phase EnvironmentalBioremediation," B.B. Looney, T.C. Hazen, S. Pfiffner, and K. Lombard.

Related patents include:

-- Patent 4,832,122, "In Situ Remediation System and Method for Contaminated Groundwater," J.C.Corey, B.B. Looney, and D.S. Kaback, assignors to the U.S. as represented by the U.S. DOE.

-- Patent 5,186,255, "Flow Monitoring and Control System for Injection Wells," J.C. Corey, assignor to theU.S. as represented by the U.S. DOE.

-- Patent 5,263,795, "In Situ Remediation System for Groundwater and Soils," J.C. Corey, D.S. Kaback,and B.B. Looney, assignors to the U.S. as represented by the U.S. DOE.

-- Patent 4,660,639, "Removal of Volatile Contaminants from the Vadose Zone of Contaminated Ground,"M.J. Visser and J.D. Malot, assignors to the Upjohn Company. WSRC paid a one-time license fee to theassignee for the use of the process with horizontal wells.

-- Patent 5,006,250, "Pulsing of Electron Donor and Electron Acceptor for Enhanced Biotransformation ofChemicals," P.V. Roberts, G.D. Hopkins, L. Semprini, P.L. McCarty, and D.M. McKay, assignors to theBoard of Trustees of the Leland Stanford Junior University.

Licensing Information? ISBR is commercially available through the WSRD Technology Transfer Office

? To date, 19 licenses have been applied for and six licenses have been granted.

CollaboratorsGovernment

U.S. Department of Energy

Savannah River SiteOak Ridge National LaboratoryHazardous Waste Remedial Actions ProgramIdaho National Engineering LaboratoryPacific Northwest LaboratoryLawrence Livermore National LaboratoryLos Alamos National Laboratory

U.S. Environmental Protection AgencyU.S. Geological SurveyU.S. Air ForceU.S. Army Corps of EngineersSouth Carolina Department of Health and Environmental Control

Academia

Stanford UniversityUniversity of South CarolinaUniversity of IllinoisUniversity of WashingtonUtah State UniversityGeorgia State UniversityUniversity of MinnesotaUniversity of Cincinnati

IndustryGas Research InstituteRadian Corp.Eastman ChristiensenWestinghouseE. I. duPont de Nemours Inc.Michigan Biotech InstituteEnvirex Inc.Bechtel Inc.GravesO'Brien and GereMonitoring Testing ServiceGeneral Engineering LabTren FuelsSouth Carolina Electric and Gas Co.Terra-Vac

Appendix E: References

1. T. C. Hazen 1991. Test Plan for In Situ Bioremediation Demonstration of the Savannah RiverIntegrated Demonstration Project, DOE/OTD TTP NO.:SR 0566-01. WSRC-RD-91-23. 88 pp.,WSRC Information Services, Aiken, SC.

2. T. C. Hazen 1993. Preliminary Technology Report for In Situ Bioremediation Demonstration(Methane Biostimulation) of the Savannah River Site Integrated Demonstration Project,DOE/OTD. WSRC-TR-93-670. 39 pp. WSRC Information Services, Aiken, SC.

3. T. C. Hazen 1995. Level 2 Summary Technology Report for In Situ BioremediationDemonstration (Methane Biostimulation) of the Savannah River Site IntegratedDemonstration Project, DOE/OTD. in press.

4. D. S. Kaback, B. B. Looney, J. C. Corey, and L. M. Wright, III 1989. Well Completion Reporton Installation of Horizontal Wells for In Situ Remediation Tests . WSRC-RP-89-784.Westinghouse Savannah River Company, Aiken, SC.

5. R. P. Saaty and S. R. Booth 1994. In Situ Bioremediation: Cost Effectiveness of a RemediationTechnology Field Test at the Savannah River Integrated Demonstration Site . Los AlamosNational Laboratory report No. LA-UR-94-1714.

6. B. J. Travis and N. D. Rosenberg 1994. Numerical Simulations in Support of the In SituBioremediation Demonstration at Savannah River. 43p. Los Alamos National LaboratoryTechnical Repot: LA-UR94-716.

7. Battelle Pacific Northwest Laboratories 1994. PROTECH Technology Information Profile for InSitu Bioremediation, PROTECH database.

8. Science Applications International Corporation 1993. Turnover Plan for the IntegratedDemonstration Project for Cleanup of Contaminants in Soils and Groundwater at Non-AridSites , SRS.

9. D. D. Wilson and D. S. Kaback 1993, Industry Survey for Horizontal Wells , WSRC-TR-93-511. WSRC Information Services, Aiken, SC.

10. C. A. Eddy Dilek et al. 1993, Post-Test Evaluation of the Geology, Geochemistry,Microbiology, and Hydrogeology of the In Situ Air Stripping Demonstration Site at theSavannah River Site . WSRC-TR-93-369 Rev.0. WSRC Information Services, Aiken SC.

11. E.I.duPont de Nemours 1982. Preliminary Technical Data Summary M-Area GroundwaterCleanup Facility, Savannah River Laboratory.

12. A. L. Ramirez and W. D. Daily 1995. Electrical Resistance Tomography During In Situ TCERemediation at the Savannah River Site , Journal of Applied Geophysics.

13. Martin Marietta HAZWRAP in conjunction with Stone and Webster and CKY 1995. (prepared forthe U.S. Department of Energy) In Situ Air Stripping Using Horizontal Wells, InnovativeTechnology Summary Report.